Ostwald Process Simulator
Ammonia to nitric acid in 3 steps
What this lesson covers
Why it matters
Ammonia gas meets oxygen over a platinum gauze, starting a sequence of reactions that ends in nitric acid.
Predict first
What is the first product formed when ammonia is catalytically oxidized?
The first step produces colourless nitric oxide (NO) and water.
- Nitrogen gas (N₂)
- Nitric oxide (NO) — correct
- Nitrogen dioxide (NO₂)
- Nitric acid (HNO₃)
What you do
Balance all three stages: 4NH₃ + 5O₂ → 4NO + 6H₂O over hot platinum, 2NO + O₂ → 2NO₂ on cooling, and 4NO₂ + 2H₂O + O₂ → 4HNO₃ in the absorption tower.
Check yourself
Which equation correctly represents the first step of the Ostwald process?
The balanced equation is 4NH₃ + 5O₂ → 4NO + 6H₂O, requiring heat and a platinum catalyst.
Why does the gas turn reddish-brown in the second stage?
Colourless NO combines with oxygen to form reddish-brown nitrogen dioxide: 2NO + O₂ → 2NO₂.
What are the reactants in the final absorption step?
The final step absorbs NO₂ in water with oxygen: 4NO₂ + 2H₂O + O₂ → 4HNO₃.
- 4NH₃ + 5O₂ → 4NO + 6H₂O — correct
- 2NH₃ + 3O₂ → 2NO + 3H₂O
- 4NH₃ + 3O₂ → 2N₂ + 6H₂O
- NH₃ + O₂ → NO₂ + H₂O
- NO reacts with O₂ to form NO₂ — correct
- NO decomposes into N₂ and O₂
- Ammonia burns with a brown flame
- Water vapour condenses
- NO₂, H₂O, and O₂ — correct
- NO, H₂O, and O₂
- NO₂ and H₂O only
- NH₃, H₂O, and O₂